Vehicle

ABSTRACT

A vehicle includes a main drive unit, a sub drive unit, and a control unit. The control unit includes a driving force distribution ratio setting unit and is configured to control the main drive unit and the sub drive unit. A drive mode of the main drive unit includes an electric power drive mode and an engine drive mode. The driving force distribution ratio setting unit is configured to set the driving force distribution ratio based on a vehicle speed, a required driving force, and the drive mode. When the drive mode is the engine drive mode, the driving force distribution ratio setting unit is configured to set the driving force distribution ratio so that a distribution ratio of the main driving force is 90% or more.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 fromJapanese Patent Application No. 2020-039007 filed on Mar. 6, 2020.

TECHNICAL FIELD

The present disclosure relates to a vehicle.

BACKGROUND ART

In recent years, a vehicle which drives both front wheels and rearwheels, a so-called four-wheel drive vehicle, has been known. Four-wheeldrive vehicles are often used for vehicles which require higher powerperformance and better ability to run on bad roads.

Due to the growing environmental awareness in recent years, higherenergy consumption efficiency is also required for four-wheel drivevehicles. Therefore, for example, JP-A-2017-105243 discloses a vehicleincluding an engine, which drives a rear wheel via a transmission, and amotor, which drives a front wheel via a clutch which can switch betweenan on state and an off state. The vehicle can be switched between anengine 2WD mode which drives only the engine, a motor 2WD mode whichdrives only the motor, and a hybrid 4WD mode which drives both theengine and the motor. By effectively utilizing the motor 2WD mode or thelike as necessary, it is possible to reduce the environmental load andthe fuel consumption.

SUMMARY OF INVENTION

However, in the vehicle of JP-A-2017-105243, since it is only possibleto switch between the engine 2WD mode, the motor 2WD mode, and thehybrid 4WD mode, there is a limit to the improvement of energyconsumption efficiency.

The present disclosure provides a vehicle capable of further improvingenergy consumption efficiency.

According to the present disclosure, there is provided a vehicleincluding a main drive unit configured to output a main driving forcefor driving one of a front wheel and a rear wheel, a sub drive unitconfigured to output a sub driving force for driving the other of thefront wheel and the rear wheel, and a control unit configured to controlthe main drive unit and the sub drive unit, in which the main drive unitincludes an internal combustion engine and at least one main driverotary electric machine, the sub drive unit includes at least one subdrive rotary electric machine, the control unit includes a driving forcedistribution ratio setting unit configured to set a driving forcedistribution ratio between the main driving force and the sub drivingforce and is configured to control the main drive unit and the sub driveunit so that the main driving force and the sub driving force have thedriving force distribution ratio set by the driving force distributionratio setting unit, a drive mode of the main drive unit includes anelectric power drive mode, in which a driving force of the main driverotary electric machine is output as the main driving force, and anengine drive mode, in which a driving force of the internal combustionengine is output as the main driving force, the driving forcedistribution ratio setting unit is configured to set the driving forcedistribution ratio based on a vehicle speed of the vehicle, a requireddriving force of the vehicle, and the drive mode of the main drive unit,and when the drive mode of the main drive unit is the engine drive mode,the driving force distribution ratio setting unit is configured to setthe driving force distribution ratio so that a distribution ratio of themain driving force is 90% or more.

According to the present disclosure, when the drive mode of the maindrive unit is the engine drive mode, the driving force distributionratio setting unit is configured to set the driving force distributionratio so that the ratio of the main driving force is 90% or more.

Therefore, the electric power consumption due to the operation of themain drive rotary electric machine and the sub drive rotary electricmachine can be reduced, and thus the energy consumption efficiency ofthe vehicle can be further improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram illustrating a schematicconfiguration of a vehicle according to an embodiment of the presentdisclosure;

FIG. 2 is an explanatory diagram illustrating power and electric powerflow when a main drive unit is in EV running (electric power drivemode);

FIG. 3 is an explanatory diagram illustrating power and electric powerflow when the main drive unit is in series running (electric power drivemode);

FIG. 4 is an explanatory diagram illustrating power and electric powerflow when the main drive unit is in engine running (engine drive mode);

FIG. 5 is a block diagram of a control unit of the vehicle of FIG. 1 ;

FIG. 6 is a diagram illustrating an electric power drive mode drivingforce distribution ratio map;

FIG. 7 is a diagram illustrating an engine drive mode driving forcedistribution ratio map; and

FIG. 8 is a diagram illustrating a modification example of the enginedrive mode driving force distribution ratio map.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment of a vehicle of the present disclosure willbe described with reference to the accompanying drawings.

As illustrated in FIG. 1 , a vehicle V of the present embodimentincludes a main drive unit DU1 and a sub drive unit DU2 which aremechanically independent. “Mechanically independent” means that power ofone drive unit is not mechanically transmitted to the other drive unitby a propeller shaft or the like. In the present embodiment, the maindrive unit DU1 outputs a main driving force to drive front wheels FWRand the sub drive unit DU2 outputs a sub driving force to drive rearwheels RWR.

The vehicle V further includes a battery BAT, a voltage control unitVCU, and a control unit CTR.

The battery BAT includes a plurality of storage cells connected inseries and supplies a high voltage of, for example, 100 V to 200 V. Thestorage cell is, for example, a lithium ion battery or a nickel hydrogenbattery.

The voltage control unit VCU boosts the output voltage output from thebattery BAT as direct current. The voltage control unit VCU steps downthe input voltage charged in the battery BAT. The voltage control unitVCU is, for example, a DC-DC converter.

[Configuration of Main Drive Unit]

First, the configuration of the main drive unit DU1 will be describedwith reference to FIG. 1 .

The main drive unit DU1 includes an engine ENG, a generator GEN, a maindrive motor MOT1, a first inverter INV1, a second inverter INV2, and afirst transmission mechanism T1. The main drive motor MOT1 and thegenerator GEN are connected to the battery BAT via the voltage controlunit VCU, the first inverter INV1, and the second inverter INV2. Themain drive motor MOT1 and the generator GEN are capable of receivingelectric power from the battery BAT and regenerating energy to thebattery BAT. The dotted line in FIG. 1 indicates the electric powerwiring and the alternate long and short dash line indicates the controlsignal line.

The first inverter INV1 converts a DC voltage into an AC voltage andsupplies a three-phase current to the generator GEN. The first inverterINV1 converts the AC voltage generated by the generator GEN into the DCvoltage.

The second inverter INV2 converts the DC voltage into the AC voltage andsupplies a three-phase current to the main drive motor MOT1. The secondinverter INV2 converts the AC voltage generated by the main drive motorMOT1 into the DC voltage when the electric vehicle is braked.

The first transmission mechanism T1 includes an input shaft 21, agenerator shaft 23, a counter shaft 25, and a first differentialmechanism D1 arranged in parallel with each other.

The input shaft 21 is arranged side by side coaxially with a crankshaft12 of the engine ENG. The power of the crankshaft 12 is transmitted tothe input shaft 21 via a damper 13. The input shaft 21 is provided withan output gear 32 forming a generator drive gear train, which will bedescribed below.

On the side of the input shaft 21 opposite to the engine ENG side, anoutput gear 53 forming an engine power transmission gear train isprovided. A hydraulic clutch CL for connecting detachably the inputshaft 21 and the output gear 53 is provided between the output gear 32and the output gear 53 on the input shaft 21.

The generator shaft 23 is a rotating shaft having a double structureincluding an inner peripheral shaft 27 and an outer peripheral shaft 29arranged concentrically with respect to the inner peripheral shaft 27 onthe outer peripheral side. An input gear 34 which meshes with the outputgear 32 on the input shaft 21 is provided on the engine ENG side of theinner peripheral shaft 27. The output gear 32 on the input shaft 21 andthe input gear 34 on the inner peripheral shaft 27 form a generatordrive gear train for transmitting the power of the input shaft 21 to theinner peripheral shaft 27.

On the outer diameter side of the inner peripheral shaft 27substantially at the center, the outer peripheral shaft 29 is installedto be relatively rotatable. The generator GEN is attached to the side ofthe inner peripheral shaft 27 opposite to the engine ENG side. Thegenerator GEN is configured to include a rotor R fixed to the innerperipheral shaft 27 and a stator S fixed to a case (not illustrated) andarranged to face the outer diameter side of the rotor R.

The driving force of the input shaft 21 is transmitted to the innerperipheral shaft 27 of the generator shaft 23 via the generator drivinggear train, so that the rotor R of the generator GEN rotates with therotation of the inner peripheral shaft 27. As a result, the drivingforce from the input shaft 21 can be converted into electric power bythe generator GEN.

An output gear 52 which meshes with an input gear 54 on the countershaft 25, which will be described below, is provided on the engine ENGside of the outer peripheral shaft 29 and the main drive motor MOT1 ismounted on the side opposite to the engine ENG side. The main drivemotor MOT1 is configured to include a rotor R fixed to the outerperipheral shaft 29 and a stator S fixed to a case (not illustrated) andarranged to face the outer diameter side of the rotor R.

The output gear 52 on the outer peripheral shaft 29 and the input gear54 on the counter shaft 25 form a motor power transmission gear trainfor transmitting the power of the outer peripheral shaft 29 to thecounter shaft 25. Therefore, when the outer peripheral shaft 29 isrotated by the driving force of the main drive motor MOT1, the rotationis transmitted to the counter shaft 25 via the motor power transmissiongear train.

The counter shaft 25 is provided with an output gear 56 which mesheswith a ring gear 58 of the first differential mechanism D1 and the inputgear 54 which meshes with the output gear 53 on the input shaft 21 andthe output gear 52 on the outer peripheral shaft 29 in order from theengine ENG side. The output gear 53 on the input shaft 21 and the inputgear 54 on the counter shaft 25 form an engine power transmission geartrain for transmitting the power of the input shaft 21 to the countershaft 25. The output gear 56 on the counter shaft 25 and the ring gear58 of the first differential mechanism D1 form a final gear train fortransmitting the driving force of the counter shaft 25 to the firstdifferential mechanism D1.

The driving force of the main drive motor MOT1 input to the countershaft 25 via the motor power transmission gear train and the drivingforce of the engine ENG input to the counter shaft 25 via the enginepower transmission gear train are output as the main driving force ofthe main drive unit DU1, are transmitted to the first differentialmechanism D1 via the final gear train, and are transmitted from thefirst differential mechanism D1 to the front wheels FWR.

The first transmission mechanism T1 of the main drive unit DU1 of theembodiment includes a first transmission mechanism 41 which connects thegenerator GEN and the engine ENG to be capable of transmitting the powerand a second transmission mechanism 42 which connects the main drivemotor MOT1 and the front wheels FWR to be capable of transmitting thepower. That is, the first transmission mechanism 41 is composed of theinput shaft 21, the output gear 32, the input gear 34, and the innerperipheral shaft 27 and the second transmission mechanism 42 is composedof the outer peripheral shaft 29, the output gear 52, the input gear 54,the counter shaft 25, the output gear 56, and the first differentialmechanism D1.

A hydraulic clutch CL is adapted to selectively switch between a statewhere the power transmission path between the first transmissionmechanism 41 and the second transmission mechanism 42 is connected and astate where the power transmission path between the first transmissionpath and the second transmission path is disconnected. That is, byengaging the hydraulic clutch CL, the power transmission path betweenthe first transmission mechanism 41 and the second transmissionmechanism 42 is connected (locked up), and by releasing the hydraulicclutch CL, the power transmission path between the first transmissionmechanism 41 and the second transmission mechanism 42 is disconnected.In the first transmission mechanism T1, the input gear 54 meshes withthe output gear 53 on the input shaft 21 and the output gear 52 on theouter peripheral shaft 29. Therefore, when the hydraulic clutch CL isengaged, the power transmission path between the first transmissionmechanism 41 and the second transmission mechanism 42 is connected andthe power transmission between the first transmission mechanism 41 andthe second transmission mechanism 42 becomes possible. On the otherhand, when the hydraulic clutch CL is released, the output gear 53 isdisengaged from the input shaft 21, so that the power transmission pathbetween the first transmission mechanism 41 and the second transmissionmechanism 42 is disconnected and the power transmission between thefirst transmission mechanism 41 and the second transmission mechanism 42becomes impossible.

[Configuration of Sub Drive Unit]

The sub drive unit DU2 includes a sub drive motor MOT2, a third inverterINV3, and a second transmission mechanism T2. The sub drive motor MOT2is connected to the battery BAT via the voltage control unit VCU and thethird inverter INV3 and is capable of receiving electric power from thebattery BAT and regenerating energy to the battery BAT. The dotted linein FIG. 1 indicates the electric power wiring and the alternate long andshort dash line indicates the control signal line.

The second transmission mechanism T2 includes a motor output shaft 26and an output shaft 28 arranged in parallel with each other and a seconddifferential mechanism D2.

The sub drive unit DU2 is attached to one end of the motor output shaft26 of the sub drive motor MOT2 so that a third drive gear 62 rotatesintegrally, and a third driven gear 64 which meshes with the third drivegear 62 and an output gear 66 are attached to the output shaft 28 whichextends parallel to the motor output shaft 26 of the sub drive motorMOT2 to rotate integrally with the output shaft 28. Therefore, thedriving force of the sub drive motor MOT2 is transmitted to the outputshaft 28 via the third drive gear 62 and the third driven gear 64, andthe driving force transmitted to the output shaft 28 is transmitted fromthe output gear 66 to the rear wheels RWR via the second differentialmechanism D2. On the contrary, the driving force from the rear wheelsRWR is transmitted to the sub drive motor MOT2 via the seconddifferential mechanism D2, the output gear 66, the output shaft 28, thethird driven gear 64, the third drive gear 62, and the motor outputshaft 26.

[Drive Mode of Main Drive Unit]

Next, the drive mode of the main drive unit DU1 will be described withreference to FIGS. 2 to 4 . FIGS. 2 to 4 are simplified configurationsrelated to the main drive unit DU1 of FIG. 1 , in which the flow ofelectric power is indicated by a dotted arrow and the flow of power isindicated by a thick solid arrow.

The drive mode of the main drive unit DU1 includes an electric powerdrive mode which outputs the driving force of the main drive motor MOT1as the main driving force and an engine drive mode which outputs thedriving force of the engine ENG as the main driving force. In theelectric power drive mode, the hydraulic clutch CL is released and thedriving force of the main drive motor MOT1 is output as the main drivingforce. The electric power drive mode includes EV running and seriesrunning described below. In the engine drive mode, the hydraulic clutchCL is engaged and the driving force of the engine ENG is output as themain driving force. The engine drive mode includes engine running, whichwill be described below.

<EV Running (Electric Power Drive Mode)>

As illustrated in FIG. 2 , in EV running, the engine ENG is put into anon-operating state and the main drive motor MOT1 is driven by theelectric power supplied from the battery BAT. That is, by driving themain drive motor MOT1 with the electric power supplied from the batteryBAT, the outer peripheral shaft 29 of the generator shaft 23 is rotatedby the driving force of the main drive motor MOT1 and the rotation istransmitted to the counter shaft 25 via the motor power transmissiongear train. The driving force of the main drive motor MOT1 transmittedas such is output as the main driving force via the final gear train andthe first differential mechanism D1, and transmitted to the front wheelsFWR.

As a result, EV running becomes possible.

<Series Running (Electric Power Drive Mode)>

As illustrated in FIG. 3 , in the series running, the engine ENG is putinto an operating state and the main drive motor MOT1 is driven by theelectric power generated by the generator GEN. That is, the drivingforce of the engine ENG is input from the input shaft 21 to the innerperipheral shaft 27 via the generator driving gear train, so that theinner peripheral shaft 27 rotates. As a result, the rotor R of thegenerator GEN fixed to the inner peripheral shaft 27 rotates andelectric power is generated by the generator GEN. The electric powergenerated by the generator GEN is supplied to the main drive motor MOT1and the main drive motor MOT1 is driven by the electric power. The outerperipheral shaft 29 of the generator shaft 23 is rotated by the drivingforce of the main drive motor MOT1 and the rotation is transmitted tothe counter shaft 25 via the motor power transmission gear train.

The driving force of the main drive motor MOT1 transmitted as such isoutput as the main driving force via the final gear train and the firstdifferential mechanism D1, and transmitted to the front wheels FWR. As aresult, so-called series running is possible in which all the drivingforce of the engine ENG is converted into electricity by the generatorGEN to drive.

<Engine Running (Engine Drive Mode)>

As illustrated in FIG. 4 , in engine running, the driving force of theengine ENG is output as the main driving force and transmitted to thefront wheels FWR with the hydraulic clutch CL in the engaged state. Thatis, by engaging the hydraulic clutch CL, the driving force of the inputshaft 21 is transmitted to the counter shaft 25 via the engine powertransmission gear train, and is transmitted to the front wheels FWR viathe final gear train and the first differential mechanism D1. Thetransmission enables engine running. Here, since the input shaft 21 andthe inner peripheral shaft 27 are always connected via the generatordrive gear train, the rotor R of the generator GEN rotates as the innerperipheral shaft 27 rotates. Therefore, the generator GEN can generateelectric power, and thus so-called parallel running is also possible inwhich the main drive motor MOT1 is rotated by the generated electricpower and the driving force of the engine ENG and the driving force ofthe main drive motor MOT1 are output as the main driving force.

[Control Unit]

The control unit CTR is a control unit which controls the entire vehicleV and controls the voltage control unit VCU, the first inverter INV1,the second inverter INV2, the third inverter INV3, the engine ENG, andthe hydraulic clutch CL of the main drive unit DU1. The control unit CTRcontrols the input/output of the main drive unit DU1 and the sub driveunit DU2.

Subsequently, the output control of the main drive unit DU1 and the subdrive unit DU2 in the control unit CTR will be described with referenceto FIGS. 5 to 7 .

As illustrated in FIG. 5 , the control unit CTR includes a requireddriving force calculation unit 71 which calculates a required drivingforce Freq of the vehicle V, a drive mode determination unit 73 fordetermining whether the drive mode of the main drive unit DU1 is theelectric power drive mode or the engine drive mode, and a driving forcedistribution ratio setting unit 75 which sets the driving forcedistribution ratio between the main driving force output by the maindrive unit DU1 and the sub driving force output by the sub drive unitDU2.

A signal indicating a vehicle speed VP of the vehicle V, which isobtained from a vehicle speed sensor 81, a signal indicating anaccelerator pedal opening AP according to the operation of theaccelerator pedal by a driver of the vehicle V, which is obtained froman accelerator pedal opening sensor 83, and a signal indicating a clutchstate CLS whether the hydraulic clutch CL is in the engaged state or thereleased state, which is obtained from a clutch sensor 85, are input.

The required driving force calculation unit 71 calculates the requireddriving force Freq of the vehicle V based on the vehicle speed VPobtained from the vehicle speed sensor 81 and the accelerator pedalopening AP obtained from the accelerator pedal opening sensor 83.

The drive mode determination unit 73 determines whether the drive modeof the main drive unit DU1 is the electric power drive mode or theengine drive mode based on the clutch state CLS obtained from the clutchsensor 85. Specifically, when the hydraulic clutch CL is in the engagedstate, it is determined that the drive mode of the main drive unit DU1is the engine drive mode, and when the hydraulic clutch CL is in thereleased state, it is determined that the drive mode of the main driveunit DU1 is the electric power drive mode.

The driving force distribution ratio setting unit 75 sets the drivingforce distribution ratio between the main driving force output by themain drive unit DU1 and the sub driving force output by the sub driveunit DU2 based on the vehicle speed VP obtained from the vehicle speedsensor 81, the required driving force Freq calculated by the requireddriving force calculation unit 71, and the drive mode of the main driveunit DU1 determined by the drive mode determination unit 73.

The driving force distribution ratio setting unit 75 stores an electricpower drive mode driving force distribution ratio map 91 illustrated inFIG. 6 and an engine drive mode driving force distribution ratio map 92illustrated in FIG. 7 .

When the drive mode of the main drive unit DU1 determined by the drivemode determination unit 73 is the electric power drive mode, the drivingforce distribution ratio setting unit 75 searches the electric powerdrive mode driving force distribution ratio map 91 based on the vehiclespeed VP obtained from the vehicle speed sensor 81 and the requireddriving force Freq calculated by the required driving force calculationunit 71 and sets the driving force distribution ratio between the maindriving force output by the main drive unit DU1 and the sub drivingforce output by the sub drive unit DU2.

When the drive mode of the main drive unit DU1 determined by the drivemode determination unit 73 is the engine drive mode, the driving forcedistribution ratio setting unit 75 searches the engine drive modedriving force distribution ratio map 92 based on the vehicle speed VPobtained from the vehicle speed sensor 81 and the required driving forceFreq calculated by the required driving force calculation unit 71 andsets the driving force distribution ratio between the main driving forceoutput by the main drive unit DU1 and the sub driving force output bythe sub drive unit DU2.

The control unit CTR controls the voltage control unit VCU, the firstinverter INV1, the second inverter INV2, the third inverter INV3, theengine ENG, and the hydraulic clutch CL of the main drive unit DU1 sothat the driving force distribution ratio between the main driving forceoutput by the main drive unit DU1 and the sub driving force output bythe sub drive unit DU2 becomes the driving force distribution ratio setby the driving force distribution ratio setting unit 75, so that thecontrol unit CTR controls the outputs of the main drive unit DU1 and thesub drive unit DU2.

As illustrated in FIG. 6 , in the electric power drive mode drivingforce distribution ratio map 91, the horizontal axis is set to thevehicle speed VP and the vertical axis is set to the required drivingforce Freq, and for each vehicle speed VP and each required drivingforce Freq, the driving force distribution ratio between the maindriving force output by the main drive unit DU1 and the sub drivingforce output by the sub drive unit DU2 is set. The electric power drivemode driving force distribution ratio map 91 of the embodimentillustrates the distribution of the main driving force output by themain drive unit DU1 when the required driving force Freq is 1.

In FIG. 6 , in the electric power drive mode driving force distributionratio map 91, the driving force distribution ratio between the maindriving force output by the main drive unit DU1 and the sub drivingforce output by the sub drive unit DU2 is illustrated in grayscale. Inthe map, the closer it is to black, the higher the distribution ratio ofthe main driving force and the lower the distribution ratio of the subdriving force, and the closer it is to white, the lower the distributionratio of the main driving force and the higher the distribution ratio ofthe sub driving force. The part illustrated in the darkest color is theportion where the distribution of the main driving force output by themain drive unit DU1 when the required driving force Freq is 1 is set to1.00, that is, the driving force distribution ratio is set as “maindriving force:sub driving force=100:0”, and thus the vehicle is drivenonly by the main drive unit DU1. The part illustrated in white is theportion where the distribution of the main driving force output by themain drive unit DU1 when the required driving force Freq is 1 is set to0.50, that is, the driving force distribution ratio is set as “maindriving force:sub driving force=50:50”. In the electric power drive modedriving force distribution ratio map 91, for all vehicle speed VP andall required driving force Freq, when the required driving force Freq is1, the distribution of the main driving force output by the main driveunit DU1 is set to 0.50 or more, that is, the driving force distributionratio is set so that the distribution ratio of the main driving forcebecomes always 50% or more.

For example, when the vehicle speed VP is 60 km/h and the requireddriving force Freq is 1200 N, the distribution of the main driving forceoutput by the main drive unit DU1 when the required driving force Freqis 1 is set to 0.70, that is, the driving force distribution ratio isset as “main driving force:sub driving force=70:30”. When the vehiclespeed VP is 40 km/h and the required driving force Freq is 2000 N, thedistribution of the main driving force output by the main drive unit DU1when the required driving force Freq is 1 is set to 0.80, that is, thedriving force distribution ratio is set as “main driving force:subdriving force=80:20”. When the vehicle speed VP is 120 km/h and therequired driving force Freq is 2000 N, the distribution of the maindriving force output by the main drive unit DU1 when the requireddriving force Freq is 1 is set to 0.60, that is, the driving forcedistribution ratio is set as “main driving force:sub drivingforce=60:40”.

In the driving force distribution ratio map in the electric powerdriving mode 91, as the driving force distribution ratio for eachvehicle speed VP and each required driving force Freq, the driving forcedistribution ratio that minimizes the electric power loss of the vehicleV is set based on the vehicle speed VP and the required driving forceFreq.

Therefore, the driving force distribution ratio setting unit 75 sets thedriving force distribution ratio to minimize the electric power loss ofthe vehicle V based on the vehicle speed VP of the vehicle V and therequired driving force Freq of the vehicle V. Therefore, the main driveunit DU1 and sub drive unit DU2 can be controlled so that the electricpower loss of the vehicle V is minimized, and thus the energyconsumption efficiency of the vehicle V can be improved.

As illustrated in FIG. 7 , in the engine drive mode driving forcedistribution ratio map 92, the horizontal axis is set to the vehiclespeed VP and the vertical axis is set to the required driving forceFreq. and for each vehicle speed VP and each required driving forceFreq, the driving force distribution ratio between the main drivingforce output by the main drive unit DU1 and the sub driving force outputby the sub drive unit DU2 is set.

In FIG. 7 , in the engine drive mode driving force distribution ratiomap 92, the driving force distribution ratio between the main drivingforce output by the main drive unit DU1 and the sub driving force outputby the sub drive unit DU2 is illustrated in grayscale. In the map, thecloser it is to black, the higher the distribution ratio of the maindriving force and the lower the distribution ratio of the sub drivingforce, and the closer it is to white, the lower the distribution ratioof the main driving force and the higher the distribution ratio of thesub driving force. The part illustrated in the darkest color is theportion where the distribution of the main driving force output by themain drive unit DU1 when the required driving force Freq is 1 is set to1.00, that is, the driving force distribution ratio is set as “maindriving force:sub driving force=100:0”, and thus the vehicle is drivenonly by the main drive unit DU1.

For example, when the vehicle speed VP is 60 km/h and the requireddriving force Freq is 1200 N, the distribution of the main driving forceoutput by the main drive unit DU1 when the required driving force Freqis 1 is set to 1.00, that is, the driving force distribution ratio isset as “main driving force:sub driving force=100:0”. When the vehiclespeed VP is 40 km/h and the required driving force Freq is 2000 N, thedistribution of the main driving force output by the main drive unit DU1when the required driving force Freq is 1 is set to 1.00, that is, thedriving force distribution ratio is set as “main driving force:subdriving force=100:0”. When the vehicle speed VP is 120 km/h and therequired driving force Freq is 2000 N, the distribution of the maindriving force output by the main drive unit DU1 when the requireddriving force Freq is 1 is set to 0.90, that is, the driving forcedistribution ratio is set as “main driving force:sub drivingforce=90:10”.

In the engine drive mode driving force distribution ratio map 92, thedriving force distribution ratio for each vehicle speed VP and eachrequired driving force Freq is set so that the distribution ratio of themain driving force is 90% or more.

Therefore, when the drive mode of the main drive unit DU1 is the enginedrive mode, the driving force distribution ratio setting unit 75 setsthe driving force distribution ratio so that the ratio of the maindriving force is 90% or more. Therefore, the electric power consumptiondue to the operation of the main drive motor MOT1 and the sub drivemotor MOT2 can be reduced, and thus the energy consumption efficiency ofthe vehicle V can be improved.

As illustrated in FIGS. 6 and 7 , when compared with the same vehiclespeed VP and the same required driving force Freq, the driving forcedistribution ratio set in the electric power drive mode driving forcedistribution ratio map 91 has the same or larger sub driving forcedistribution ratio than the driving force distribution ratio set in theengine drive mode driving force distribution ratio map 92. Therefore,the distribution ratio of the sub driving force, in the driving forcedistribution ratio when the drive mode of the main drive unit DU1 is theelectric power drive mode, is the same or larger than the distributionratio of the sub driving force, in the driving force distribution ratiowhen the drive mode of the main drive unit DU1 is the engine drive mode.

Therefore, the main drive unit DU1 includes the engine ENG, and in thedriving force distribution ratio when the drive mode of the main driveunit DU1 is the electric power drive mode, the distribution ratio of thesub driving force is the same or larger than that of the driving forcedistribution ratio when the drive mode of the main drive unit DU1 is theengine drive mode. Thus, when the drive mode of the main drive unit DU1is the electric power drive mode, the loss caused by the main drive unitDU1 can be further reduced. As a result, the energy consumptionefficiency of the vehicle V can be improved.

FIG. 8 illustrates an engine drive mode driving force distribution ratiomap 93, which is a modification example of the engine drive mode drivingforce distribution ratio map 92.

The engine drive mode driving force distribution ratio map 92 may be theengine drive mode driving force distribution ratio map 93.

In the engine drive mode driving force distribution ratio map 93, forall vehicle speed VP and all required driving force Freq, when therequired driving force Freq is 1, the distribution of the main drivingforce output by the main drive unit DU1 is set to 1.00, that is, thedriving force distribution ratio is set as “main driving force:subdriving force=100:0”. Therefore, the distribution ratio of the subdriving force is 0, and thus the vehicle is driven only by the maindrive unit DU1.

Therefore, when the drive mode of the main drive unit DU1 is the enginedrive mode, the driving force distribution ratio setting unit 75 setsthe driving force distribution ratio so that the ratio of the subdriving force becomes 0. Thus, the electric power consumption due to theoperation of the main drive motor MOT1 and the sub drive motor MOT2 canbe reduced by simple control. As a result, the energy consumptionefficiency of vehicle V can be improved by simple control.

Thus, according to the electric power drive mode driving forcedistribution ratio map 91 and the engine drive mode driving forcedistribution ratio maps 92 and 93, in the driving force distributionratio setting unit 75, the driving force distribution ratio is set sothat the distribution ratio of the main driving force is always 50% ormore.

Therefore, the main drive unit DU1 includes the engine ENG and thedriving force distribution ratio setting unit 75 sets the driving forcedistribution ratio so that the distribution ratio of the main drivingforce is 50% or more. Thus, the engine ENG, the main drive motor MOT1,and the sub drive motor MOT2 can be operated more efficiently. As aresult, the energy consumption efficiency of the vehicle V can beimproved.

Although the embodiment of the present disclosure is described above,the present disclosure is not limited to the embodiment described aboveand can be appropriately modified, improved, and the like.

For example, in the embodiment, the main drive unit DU1 outputs the maindriving force to drive the front wheels FWR and the sub drive unit DU2outputs the sub driving force to drive the rear wheels RWR. However, themain drive unit DU1 may output the main driving force to drive the rearwheels RWR and the sub drive unit DU2 may output the sub driving forceto drive the front wheels FWR.

At least the following matters are described in the specification. Thecomponents and the like corresponding to those of the embodimentdescribed above are shown in parentheses, but the present disclosure isnot limited to these.

(1) A vehicle (vehicle V) including:

a main drive unit (main drive unit DU1) configured to output a maindriving force for driving one of a front wheel (front wheel FWR) and arear wheel (rear wheel RWR);

a sub drive unit (sub drive unit DU2) configured to output a sub drivingforce for driving the other of the front wheel and the rear wheel; and

a control unit (control unit CTR) configured to control outputs of themain drive unit and the sub drive unit, in which:

the main drive unit includes an internal combustion engine (engine ENG)and at least one main drive rotary electric machine (main drive motorMOT1);

the sub drive unit includes at least one sub drive rotary electricmachine (sub drive motor MOT2);

the control unit includes a driving force distribution ratio settingunit (driving force distribution ratio setting unit 75) configured toset a driving force distribution ratio between the main driving forceand the sub driving force and is configured to control the outputs ofthe main drive unit and the sub drive unit so that the main drivingforce and the sub driving force have the driving force distributionratio set by the driving force distribution ratio setting unit;

a drive mode of the main drive unit includes an electric power drivemode, in which a driving force of the main drive rotary electric machineis output as the main driving force, and an engine drive mode, in whicha driving force of the internal combustion engine is output as the maindriving force:

the driving force distribution ratio setting unit is configured to setthe driving force distribution ratio based on a vehicle speed (vehiclespeed VP) of the vehicle, a required driving force (required drivingforce Freq) of the vehicle, and the drive mode of the main drive unit,and

when the drive mode of the main drive unit is the engine drive mode, thedriving force distribution ratio setting unit is configured to set thedriving force distribution ratio so that a distribution ratio of themain driving force is 90% or more.

According to (1), when the drive mode of the main drive unit is theengine drive mode, the driving force distribution ratio setting unit isconfigured to set the driving force distribution ratio so that the ratioof the main driving force is 90% or more. Therefore, the electric powerconsumption due to the operation of the main drive rotary electricmachine and the sub drive rotary electric machine can be reduced, andthus the energy consumption efficiency of the vehicle can be improved.

(2) The vehicle according to (1), in which

the driving force distribution ratio setting unit is configured todetermine the driving force distribution ratio so that a distributionratio of the sub driving force becomes zero when the drive mode of themain drive unit is the engine drive mode.

According to (2), when the drive mode of the main drive unit is theengine drive mode, the driving force distribution ratio setting unit isconfigured to determine the driving force distribution ratio so that theratio of the sub driving force becomes zero. Therefore, the electricpower consumption due to the operation of the main drive rotary electricmachine and the sub drive rotary electric machine can be reduced bysimple control, and thus the energy consumption efficiency of thevehicle can be improved by simple control.

(3) The vehicle according to (1) or (2), in which

the driving force distribution ratio setting unit is configured todetermine the driving force distribution ratio so that a ratio of themain driving force is 50% or more.

According to (3), the drive control unit is configured to determine thedriving force distribution ratio so that the ratio of the main drivingforce is 50% or more. Therefore, the internal combustion engine, themain drive rotary electric machine, and the sub drive rotary electricmachine can be operated more efficiently, and thus the energyconsumption efficiency of the vehicle can be improved.

What is claimed is:
 1. A vehicle comprising: a main drive unit configured to output a main driving force for driving one of a front wheel and a rear wheel; a sub drive unit configured to output a sub driving force for driving the other of the front wheel and the rear wheel; and a control unit configured to control the main drive unit and the sub drive unit, wherein: the main drive unit includes an internal combustion engine and at least one main drive rotary electric machine; the sub drive unit includes at least one sub drive rotary electric machine; the control unit includes a driving force distribution ratio setting unit configured to set a driving force distribution ratio between the main driving force and the sub driving force and is configured to control the main drive unit and the sub drive unit so that the main driving force and the sub driving force have the driving force distribution ratio set by the driving force distribution ratio setting unit; a drive mode of the main drive unit includes an electric power drive mode, in which a driving force of the main drive rotary electric machine is output as the main driving force, and an engine drive mode, in which a driving force of the internal combustion engine is output as the main driving force; the driving force distribution ratio setting unit stores a first driving force distribution ratio map of the electric power drive mode and a second driving force distribution ratio map of the engine drive mode; when the drive mode of the main drive unit is the electric power drive mode, the driving force distribution ratio setting unit is configured to set the driving force distribution ratio based on a vehicle speed of the vehicle, a required driving force of the vehicle, and the first driving force distribution ratio map; when the drive mode of the main drive unit is the engine drive mode, the driving force distribution ratio setting unit is configured to set the driving force distribution ratio based on a vehicle speed of the vehicle, a required driving force of the vehicle, and the second driving force distribution ratio map; and when the drive mode of the main drive unit is the engine drive mode, the driving force distribution ratio setting unit is configured to set the driving force distribution ratio so that a distribution ratio of the main driving force is 90% or more based on the second driving distribution ratio map.
 2. The vehicle according to claim 1, wherein the driving force distribution ratio setting unit is configured to determine the driving force distribution ratio so that a distribution ratio of the sub driving force becomes zero when the drive mode of the main drive unit is the engine drive mode.
 3. The vehicle according to claim 1, wherein the driving force distribution ratio setting unit is configured to determine the driving force distribution ratio so that a ratio of the main driving force is 50% or more. 